#include <stdio.h>
#include <math.h>

int main(){
    double a, b, c, area, p;
    printf("请输入三角形的三条边:");
    scanf("%lf,%lf,%lf", &a, &b, &c);
    if ((a + b > c) && (a + c > b) && (b + c > a)){
        p = (a + b + c) / 2;
        area = sqrt(p * (p - a) * (p - b) * (p - c));
        printf("三角形的面积为：%f\n", area);
        return 0;
    }else{
        printf("您输入的三边不能构成三角形");
        return 0;
    }
}